The present invention relates to torque transmitting and torsion damping assemblies, and more particularly to a torque transmitting and torsion damping assembly which can be utilized in motor vehicles, especially for the transmission of torque between the crankshaft of an internal combustion engine and the input element of a change-speed transmission, and which is or can be equipped with torsion damping means for taking up and counteracting the shocks which develop during transmission of torque in motor vehicles or the like. Still more particularly, the invention relates to improvements in torque transmitting assemblies of the type wherein two coaxial flywheels are angularly movable relative to each other within certain limits against the opposition of a damper which transmits torque between and yieldably opposes rotation of the two flywheels relative to each other, wherein one of the flywheels can receive torque from the engine and wherein the other flywheel can transmit torque to the transmission. Still more particularly, the invention relates to improvements in torque transmitting assemblies of the type wherein the other flywheel transmits or can transmit torque to the input element of the change-speed transmission in response to engagement of a clutch. Thus, by engaging or disengaging the clutch by way of a suitable actuating device, the operator of the motor vehicle can initiate or terminate the transmission of torque between the engine and the transmission.
It is already known to install an antifriction bearing between the two flywheels of the above outlined torque transmitting assembly. The mounting of the bearing is such that one race of the bearing is rigid with the one flywheel and the other race is rigid with the other flywheel. Such mounting of the bearing between the two flywheels is not entirely satisfactory for a number of reasons. First of all, and since the flywheels are normally confined to rotation relative to each other through a small or very small angle, the two races are invariably and necessarily confined to the same angular movement relative to each other. In other words, each and every angular position of one race relative to the other race is a function of the angular position of the one flywheel with reference to the other flywheel. This creates serious problems when the motor vehicle is operated under load and one of the flywheels performs angular movements relative to the other flywheel at a high or extremely high frequency but at a small or extremely small amplitude. As a rule, the amplitude is not in excess of, and is normally much less than, one degree. Consequently, the extent to which the spherical, roller-shaped, needle-like or otherwise configurated rolling elements between the two races can roll, spin or turn during such high-frequency, low-amplitude angular movement of one of the flywheels relative to the other flywheel and/or vice versa is extremely small. As a rule, each rolling element merely rolls back and forth along one and the same portion of each of the two races with the result that the wear upon such portions of the races, and upon the corresponding portions of the rolling elements, is much more pronounced than the wear upon the remaining portions of the races and rolling elements. Repeated rolling of each rolling element along one and the same portion of each of the two races entails localized overstressing of the material of the two races. In fact, the rolling elements are likely to form in the races recesses in the form of depressions in the respective tracks which leads to practically immediate or very rapid destruction of the races. Moreover, such repeated rolling of the rolling elements along relative small portions of the races entails cracking and/or chipping of the races as well as of the rolling elements with the same result, i.e., the bearing becomes useless and must be replaced. A further serious drawback of the aforementioned repeated and frequent rolling of each spherical or otherwise configurated rolling element through a small or extremely small angle and along one and the same portion of each of the two races affects the quality of the lubricating action, i.e., the rolling elements are unable to adequately spread the lubricant along the tracks of the two races.
A torque transmitting assembly with a damper between the flywheels is disclosed, for example, in German Offenlegungsschrift No. 28 26 274. The assembly of this German printed publication employs a first flywheel which is driven by the crankshaft of the engine and has an axially extending central protuberance for a sleeve which is surrounded by the other flywheel. The sleeve has a radial flange which is disposed between the two flywheels and takes up the force that develops during engagement of the friction clutch. Such force is transmitted to the flywheel which receives torque from the crankshaft of the engine. Thus, the force with which the radial flange of the sleeve between the two flywheels is compressed increases drastically when the clutch is being engaged and the flange then generates a very pronounced moment of friction which is effective between the two flywheels. In many instances, a pronounced moment of friction during certain stages of operation of the clutch is not only unnecessary but acutally highly undesirable because it adversely influences the operation of the damper between the two frictional wheels. The adverse influence of excessive friction between the two flywheels is especially pronounced during actual engagement or disengagement of the clutch, particularly a friction clutch. Thus, the engine continues to remain in torque-transmitting engagement with the input element of the change-speed transmission during a substantial part of movement of the release element (such as a bearing) from the one to the other of its end positions. If the friction clutch employs a diaphragm spring with radially inwardly extending prongs which are acted upon by the release bearing, the two flywheels remain locked to each other (as a result of pronounced compression of the aforementioned radial flange) during the major part of axial movement of the tips of the prongs from the positions which they assume when the clutch is disengaged to the positions they assume in engaged condition of the clutch or vice versa. This enables the engine to transmit to the transmission vibrations of very high amplitude or vice versa which not only results in excessive stressing of the power train between the engine and the wheels or other driven parts but also affects the comfort of the occupant or occupants of the vehicle. The discomfort is caused by the generation of excessive noise and/or by excessive vibrations.
U.S. Pat. No. 4,351,167 to Hanke et al. discloses an elastic disc-type coupling wherein a single flywheel confines a disc and defines two chambers with a flow restrictor between the chambers. The tendency of the flywheel and of the disc to turn relative to each other is opposed by the liquid which is confined in the chambers. The patent does not propose to use antifriction bearings between the disc and the single flywheel.
A twin-flywheel firction clutch is disclosed in U.S. Pat. No. 4,274,524 to Nakane. This patentee proposes to employ a bushing which surrounds an axially extending protuberances of one of the flywheels and is surrounded by a plate driven by the other flywheel. The two flywheels have some freedom of angular movement relative to each other.